1. Field of the Invention
The present invention relates to a direct methanol fuel cell, and in particular, to a 7-layered membrane-electrode-assembly (MEA7) of a direct methanol fuel cell.
2. Description of the Related Art
Developed 3C (Computer, Communication and Consumer Electronic) products consume more and more power to meet improved function requirements. Requirements of Battery requirements also include high security and convenience, in addition to being lightweight. The size and weight of batteries directly affect their lifespan and size and weight of 3C products. Therefore, fuel cells play an important role in 3C products.
A direct methanol fuel cell (DMFC) using methanol as fuel has high power density of 5000 Whr/L. The DMFC uses methanol to replace hydrogen as fuel. Protons and electrons generated by chemical reactions at the anode of the DMFC reach the cathode by passing through a membrane and the outside circuits. The membrane for the conventional DMFC, contacts methanol over a long period of time, so that methanol at the anode penetrates the membrane to contact the cathode. Therefore, the cathode formed by the catalyst is poisonous and efficiency of the DMFC is reduced. Conventional processes use thick (for example, 5 mil and 7 mil) membranes to solve the aforementioned problem.
The conventional DMFC stack is generally composed by ten to twenty pieces of membrane-electrode-assemblies (MEAs), corresponding gas diffusion layers (GDLs) and flowboards. To reduce DMFC stack leakage resulting from misalignment during the assembly process, preferably, the 5-layered membrane-electrode-assembly (MEA5) composed by the MEA and the GDLs are assembled first; thereby facilitating subsequent assembly processes. The thicker membranes reduce poisons of the cathode, however, the thicker membranes more easily shrink or expand (change size) when absorbing the methanol liquid solution. Therefore, tight sealing of the MEA5 with the flowboards is difficult. Meanwhile, membranes formed by fluorine carbon materials have chemical stability properties and adherence to epoxy, silicon rubber or acrylic glue is difficult. Therefore, using conventional processes, it is hard to assembly the MEA, the GDLs and the flowboards or package materials when forming a module.
Thus, a novel direct methanol fuel cell and method for fabricating the same are desired.